District voters overwhelmingly approved charter amendments that would allow the council to expel a council member for “gross misconduct” and would require the mayor or a council member to resign immediately if convicted of a felony.

The three charter amendment measures came after a tumultuous year in local politics, with federal investigations of D.C. Council members and the 2010 campaign of Mayor Vincent C. Gray (D) leading to resignations, guilty pleas and prison time.

The two ballot measures aimed at elected officials convicted of felonies would also ban them from holding the office again.

With all the precincts reporting, the expulsion amendment had 86 percent of the vote while the mandatory resignation measures applying to the council and mayor both had 78 percent.

Many voters said in interviews that they supported the measures as a step forward to clean up city government.

“A lot of D.C. politicians believe they’re above the law,” said Foggy Bottom resident Anice Nelson, 68, after she voted to support all three referenda at the West End Neighborhood Library.

But Council Chairman Phil Mendelson (D) said the D.C. Board of Elections misinterpreted the legislation the council approved in December that placed the measures on the ballot. He said the legislation never made the leap to a lifetime ban from office. “I wrote to the board and said, ‘You’ve made a mess.’ ”

Mendelson’s Oct. 9 letter, however, was not a formal appeal, and the ballot language was already set by May, the board concluded. “If this [conviction] ever happens, somebody’s going to challenge it,” Mendelson said.

Until June, Mendelson, who was expected to easily win the election for chairman Tuesday, was a longtime at-large member. He was appointed chairman by his colleagues a week after Kwame R. Brown resigned in advance of pleading guilty to a misdemeanor campaign finance violation and to falsifying information to obtain bank loans worth more than $200,000. Prosecutors are recommending that Brown be sentenced to six days in jail, two years’ supervised release and 200 hours of community service. He is scheduled to be sentenced Nov. 13.

Brown was the second council member to resign this year. In January, Harry Thomas Jr., now serving a three-year sentence, resigned his Ward 5 council seat a day before pleading guilty to stealing more than $350,000 in funds that were designated for youth programs.

The new law would not have applied to Thomas and Brown because they resigned before they were convicted.

Under the expulsion amendment, it would take a five-sixths vote or 11 of 13 council members to remove a fellow member for gross misconduct. The council would not have the power to remove the mayor.

Rachel Karas contributed to this report.